The present invention relates to tape measures; particularly tape measure end hooks.
Coiled tape measures normally include a housing in which a coiled tape resides when not in use. Usually, the tape is extracted from the housing by hand and is retractable by hand, a spring operated device, or other similar means. Commonly, an end hook is attached to the end of the tape measure. The end hook serves several purposes. For instance, the end hook prevents the tape from being fully withdrawn into the housing so that the end of the tape becomes inaccessible to the user. In addition, the tape measure end hook provides a convenient way for the user to grab the end of the tape measure so that it may be extracted from the housing. Furthermore, the tape measure end hook may be attached to a reference point, thus eliminating the need for a user to hold the end of the tape at the reference point.
Prior art tape measure end hooks are typically sheet metal bent to form a right angle and are attached to the tape measure by one or more rivets. Usually the hook is attached to the tape in such a manner as to allow the hook to float, i.e. move a short distance along the longitudinal axis of the tape. Such an arrangement is used to allow the tape measure to be used in situations where the inside surface of the hook engages the edge of an object, as well as situations where the outside edge of the hook abuts an edge. Allowing the end hook to move along the longitudinal axis of the tape compensates for any mismeasurement that might occur due to the thickness of the end hook itself.
Several types of rivet placements are known for floating end hook tape measures. One such arrangement uses a single rivet centrally positioned along the longitudinal axis of the measuring tape. Other arrangements use two or more rivets positioned along the longitudinal axis of the measuring tape. It has been found that in single rivet designs, the rivet is subject to a large amount of stress from the edge of the end hook opening when the tape is retracted into the measuring tape housing. In designs in which two or more rivets are mounted along the longitudinal axis of the measuring tape, it has been found that due to tolerances allowed in piercing holes in tapes and end hooks, it is quite likely that one of the two or more rivets will take the full stress load of impact when the end hook hits the housing case front.
The effects of stress on a rivet accumulate over time resulting eventually in the failure of the rivet. Rivet failure in a tape measure effectively shortens the useful life of the tape measure, since the end hook will no longer be able to function properly. Therefore, there is a need to provide a tape measure end hook which will reduce the stress placed on the rivets used to attach it to a tape and thereby increase the useful life of the tape measure.